Nice, so here there is a way to play PDS pretty easily since ROMs are available for free ?

I wouldn’t call it “free” (though if you own the game, it’s probably legal to download it), but yes, it’s definitely playable on SSF. I haven’t finished the game on Yabause, but I imagine it’s advanced far enough to be playable there as well.

Eliot-Ness:

Regarding IPs, I didnt know they had licenced Shenmue3 since it seemed SEGA was not supporting the project at all…

They’re not really supporting it, in the sense that they only granted Yu Suzuki the right to use the license. They’ll likely get royalties from it, so there’s little risk for them other than damaging the Shenmue name if the game doesn’t live up to expectations.